Anionic iodine complexes



United States Patent Ofiice 3,039,916 Patented June 19, 1962 3,039,916ANIONIC IODINE COMPLEXES Otto E. Neracher, Mount Vernon, and WilliamSchmidt and Murray W. Winicov, Flushing, N.Y., assignors to WestLaboratories, Inc., Long Island City, N.Y., a corporation of New York NoDrawing. Filed Mar. 27, 1961, Ser. No. 98,302 19 Claims. (Cl. 167-17)This invention relates to new germicidal compositions in which iodine iscomplexed with certain anionic detergents providing products havingunusual iodine stability. More particularly, the invention relates to anew group of germicidal compositions wherein iodine is complexed withanionic detergents of the alkanoyl taurate series in the presence ofiodide, and to certain of the compositions within such group which havelow foaming characteristics especially adapting them to particular uses.

The developments of the past decade in the field of surface activecarrier-iodine complexes have shown that a considerable number ofnonionic and cationic surface active agents can be employed as iodinecarriers, but that anionic surface active agents are generally notcapable of providing stable iodine formulations. One exception to thisgeneral observation is found in the alkyl aryl sulfonates, such as alkylbenzene sodium sulfonate and alkyl naphthyl sodium sulfonate, iodinecomplexes of which are disclosed and claimed in a joint application ofone of the present applicants, Serial No. 718,959, issuing March 28,1961, as United States Patent No. 2,977,- 278.

It has also been found, and separately disclosed and claimed in apending application Serial No. 55,732, filed September 13, 1960, of twoof the present applicants, that with nonionic and cationic surfaceactive agents which are good complexers of iodine, the firmness of thebinding or complexing of iodine is markedly enhanced by a source ofiodide (I) in excess of about 0.25 part per part of iodine, supplied byH1 or an alkali metal iodide. With the anionic alkyl aryl sulfonates,however, the presence of iodide has little effect on the complexing ofiodine.

It is now discovered, in accordance with the present invention that asmall group of anionic surface active agents, known per se and generallyreferred to as alkanoyl taurates, will form complexes with iodine whichare dis tinctly superior to the alkyl aryl sulfonate complexes.Furthermore, the alkanoyl taurate-iodine complexes have been found toexhibit markedly enhanced iodine complexing in 'the presence of a sourceof iodide (I-). Indeed, the new alkanoyl taurate-iodine-iodidecompositions of the present invention provide for the first time anioniccarrier-iodine products which are comparable with the nonioniccarrier'iodine products in the area of iodine complexing and stability.

The anonic surface active agents useful in accordance with the presentinvention are a small and well defined group of alkanoyl taurates whichcan be represented by the formula:

wherein R is the radical C H CO, x being an integer from 5 to 17, R isselected from the group consisting of hydrogen, lower (C to C alkyl, andcyclohexyl radicals, and Y is selected from the group consisting ofhydrogen and salt forming cations.

As with other surface active carrier-iodine compositions, the newcompositions of the present invention can be prepared in the form ofsolid formulations or concentrated solutions for dissolving in ordilution with water to provide use solutions which may vary from a fewparts per million to several hundred parts per million of iodinedepending on the particular use intended. In any such formulations,however, the proportions of carrier, iodine and iodide should fallwithin certain preferred ranges regardless of the amount of water orother diluent that may be present in a liquid or solid concentrate asintended (as products) for sale and distribution. Practical commercialproducts may range in iodine content from about 0.05% to 20% iodine,with suitable general purpose products having an iodine content of about0.5 to 2.5%.

The proportion of alkanoyl taurate to iodine is sui-tably within therange of about 2 to 1 to about 50 to 1 and preferably within the rangeof about 5 to 1 to about 20 to 1. The proportion of iodide (1*) toiodine should be in excess of 0.25 :1 and preferably about 0.421 toabout 5:1 with the further limitation that the amount of iodide shouldbe suflicient to provide a distribution coefiicient, D.C. (ashereinafter described) in excess of 25 and preferably in excess of 50.This iodide (1*) is suitably supplied either by HI or an alkali metaliodide.

Distribution coefiicient is a measure of iodine complexation incarrier-iodine compositions which is determined by a method employing aclosed equilibrium type system and depending on the equilibrium ofiodine between an aqueous solution containing complexing agent orcarrier and a non-miscible solvent, heptane. The initial amount ofiodine in the aqueous solution is determined by ordinary thiosulfatetitration; the final iodine concentration in the heptane is determinedcolorimetrically; and the amount of iodine remain ng in the aqueousphase is then found by difference. Excellent reproducibility ispossible, making the procedure a useful tool in evaluating even smalldifferences between similar compositions.

The distribution coefiicient (DC) as herein employed is determined byadding 1.00 ml of standardized test solution containing between about0.05 and 5.0% iodine to a 50 ml. graduated cylinder containing 25 mls.of purified n-heptane. The temperature of the heptane is brought to25:1" C. The cylinder is stoppered and shaken vigorously by hand for oneminute during which time the aqueous solution suspends in the heptane asa uniform haze. The solution is then allowed to, stand a minute or two,and the temperature adjustment and shaking are repeated. For bestresults, the solution should settle for an hour, although only a minuteor two are necessary if centrifuged.

The amount of iodine in the heptane layer can be determinedcolorimetrically at 520 1111;, the absorption peak; the relationshipbetween light absorption and iodine concentration in the solvent islinear through the range 1 to 25 mg. per ml. The distributioncoefficient is calculated by the following formula:

mg. I remaining in aq. phase D.C.=

mg. I in heptane Using the Beckman colorimeter with 1.00 cm. cells anabsorption of 0.142 corresponds with 1.00 mg. iodine extracted by 25mls. heptane. Values so obtained are readily reproducible to within andfrequently to within 1%.

Preparation of complexes in accordance with the present invention can beeifected by simple mixing of the alkanoyl taurate and iodine underanhydrous or aqueous conditions with the iodide source being introducedconcurrently or subsequent to the combining of the iodine and carrier.There is special advantage, however, in adding the desired amount ofcarrier to an aqueous iodine medium providing a source of iodide (I-) inexcess of about 0.25 part per part of of iodine. In this Way, a stableproduct can be readily obtained without heating or ageing.

'In adapting compositions in accordance with the present invention tospecial uses, it is sometimes desirable to incorporate other acidicand/or surface active components. Thus, for example, germicidalformulations intended for use in the dairy or food handling industries,or in other areas where large amounts of organic soil are encountered,should preferably contain an acid, such as phosphoric acid orhydroxyacetic acid in an amount sutficient to provide a pH below about4, and suitably about pH 3 in the intended use dilution. For thispurpose, the amount of acid may be as high as 5 O to 60% by weight ofthe formulation.

Special problems also arise in the germicidal cleaning of equipment andpipelines used in certain food handling industries, and particularly inthe dairy industry due to the normal foaming tendencies of surfaceactive carrieriodine formulations. It has been found that compositionsin accordance with the present invention, and particularly thosecontaining an octanoyl-subst-ituted taurate as carrier, can provide lowfoaming properties especially adapting them for such uses. The optimumlow foaming characteristics are achieved when the product contains asmall amount, i.e. to 50% of the weight of the iodine present, of anonionic surface active agent which can be described as a nonylphenolethylene oxide condensate containing about 1.5 mols of ethylene oxideper mol of nonyl phenol. This material, although itself water insoluble,goes into solution in the iodine formulation providing a stable product,and one which is unique in its low foaming properties While retaininggood detergent and excellent germicidal properties.

The following examples will provide a better understanding of typicalgermicidal compositions in accordance with the present invention, but itis to be understood that these examples are given by way of illustrationand not of limitation.

mls. heptane mls. aq. phase Example I A group of alkanoyl taurate-iodinecompositions were prepared containing 10% by weight of the alkanoyltaurate and approximately 1% of iodine in aqueous solution with variedamounts of iodide supplied by HI. These compositions have aconcentration of iodine adapting them for use as general purposegermicidal products (for distribution and sale).

The variation in the structure of the alkanoyl taurates will beunder-stood from the formula:

and the identification of the substituents R and R in the followingtabulation. For each of the difierent taurates employed distributioncoefficient, D.C., values, determined as above described, are given atfour different io-- dide. (1*) concentrations as identified in thetable:

Carrier Percent Titrat- 0.4 1.0 2.0 4.0

able

R R Iodine 05111100.... 0113 1.5 18 39 73 131 O7Hi5CO.. H 1.00 11 22 4448 do CH3 1.06 41 194 405 (lo cyclo 1.1 98 140 191 347 hexyl.

011112300- OH; 1.1 46 100 178 440 do CHsCHz" 1.14 43 100 144 303 docyclo- 0.93 s1 s0 111 190 hexyl. 01332100. CH3 1.05 22 28 60 Ci1 a5CO-CH3 (1) With respect to item 1' the solubility of the carrier and theresulting iodine-iodide complexes was too low to permit comparison underthe test conditions (10% carrier and approximately 1% iodine in aqueoussolution). These complexes are suitable, however, for use in aqueousproducts containing 1% carrier and about 0.1% iodine (practical forcertain types of germicidal products), as well as in solid productsintended fog preparation of use solutions containing less than 0.1% 10me.

Bearing in mind that a product, to be of high quality from thestandpoint of iodine stability, if it is to be stored as an aqueoussolution, must have a distribution coefficient in excess of 25, andpreferably in excess of 50, it is evident that with proper selection ofthe amount of iodide, all of the compositions containing alkanoyltaurate carriers provide high quality products.

Example II A number of alkanoyl taurate-iodinecompositions were preparedrepresentative of products for use in food handling industries, i.e.containing phosphoric acid, and in some instances also containing asanti-foaming agent a nonyl phenol ethylene oxide condensate containingabout 1.5 mols of ethylene oxide per mol of nonyl phenol. Thesecompositions were prepared by dissolving the indicated amount of iodinein an aqueous solution of the taurate, and then adding the phosphoricacid and antifoam agent. All of the compositions were found to be stableat room temperature and at F. for a period of at least two weeks. Allwere tested for foaming characteristics as determined by a newly.devised dynamic foam test method at dilutions which provides a 25 p.p.m.iodine concentration. 'In this method ml. of the solution to be testedis placed in a 500 ml. calibrated gas washing bottle with frittedcylinder. Using an air flow meter, the air flow is adjusted to 2 litersper minute and the foam height is read after equilibrium has beenreached at a temperature of 25 C. Foam values of 50 to 75 cc. representpreferred formulations for pipelineand equipment cleaning and other useswhen low foaming is important, although even formulations having foamvalues as high as 125 are considered low foam products. All of thecompositions were also tested by the method hereinabove described todetermine distribution coefficient (D.C.).

The result are tabulated below with the various taurates beingidentified with reference to the following formula:

RI;l-CH,CH SO;Na

and the changes in the substituents R and R as noted in the table. Allpercentages are by weight based on the weight of the completeformulation:

Carrier Percent Percent Percent Percent An Foam, D O

1: H3130; F0811] 00. R R

a @oo- H. 9 1.5 so so 20 H11O0 (1m 6 1. 5 30 160 19 07111500 PH. 4 o. 5a0 0. 50 19 C1H15CO 0H. s 0. 5 30 0.15 100 30 01131500 on. 6 0. 5 30 0.25 70 31 C1H15CO CH3 4 1.5 30 0.25 60 3Q C7H15CO 0H3 5 1.5 30 0.25 65 3701H1500 CH1 5 1. 5 30 0. 25 so 53 C1Hi5CO CH5 10 1.5 30 0.6 50 7s C H1OO CH1 6 1.5 so 150 47 01111500 on. 5 1. 5 55 0. a5 60 52 C1H15CO015150111 6 1.5 30 0.25 50 47.7

It will be understood that the foregolng table shows D.C. 6. Agermicidal composition as defined 1n claim 1 con- Values for heformulations without iodide. Addition of iodide provide a markedincrease in D.C. values (and iodine stability) in the manner indicatedin Example I. The following example will illustrate the typical eifectof added iodide in such complex formulations.

Example III Three formulations similar to those in Example 11 wereprepared using dilfering amounts of iodide added as HI and thecomparative distribution coefiicients determined. The pertinent data andresults are tabulated below, amounts of components being expressed inparts by weight:

Various changes and modifications in the alkanoyl taurate-iodinecomplexes of the present invention and the utilization thereof inspecial purpose formulations will occur to those skilled in the art, andto the extent that Such changes and modifications are embraced by theappended claims, it is to be understood that they constitute part of ourinvention.

We claim:

1. A germicidal composition comprising a complex of iodine with analkanoyl taurate of the formula:

RN OH2CH2S OsY wherein R is a radical of the formula C H CO with x beingan integer from 5 to 17, R is selected from the group consisting ofhydrogen, lower (C to C alkyl and cyclohexyl radicals, and Y is selectedfrom the group consisting of hydrogen and salt forming cations, theproportion of alkanoyl taurate to iodine being within the range of about2:1 to 50:1 and preferably about 5:1 to 20:1.

2. A germicidal composition as defined in claim 1 wherein the amount ofiodine present is between about 0.05% and 20%.

3. A germicidal composition as defined in claim 1 wherein the amount ofiodine present is about .5-2.5%.

4. A germicidal composition as defined in claim 3 wherein the alkanoyltaurate is an n-octanoyl-substituted taurate.

5. A germicidal composition as defined in claim 1 wherein Y is sodium.

ml. heptane ml. aq. phase D 0 mg. I in aqueous ph. mg. I in heptane 7. Agermicidal composition as defined in claim 6 wherein the iodideziodineratio is Within the range of about 0.4:1 to 5:1.

8. A germicidal composition as defined in claim 1 containing an amountof an acid selected from the group con sisting of phosphoric acid,hydroxyacetic acid and mixtures thereof suflicient to provide a pH belowabout 4 in intended use dilutions of such composition, and furthercontaining an amount, Within the range of about 15 to 50% based on theweight of the iodine present, of a nonylphenol ethylene oxide condensatehaving about 1.5 mols of ethylene oxide per mol of nonylphenol.

9. A germicidal composition as defined in claim 8 containing an iodideselected from the group consisting of H1 and alkali metal iodides in anamount to provide an iodideziodine ratio in excess of about 0.25:1 andsufficient to provide a distribution coeflicient in excess of about 25as determined by the equation:

mg. I in aqueous ph. ml. heptane D. C.=

mg. I in heptane ml. aq. phase 10. A germicidal composition as definedin claim 9 wherein the iodideziodine ratio is within the range of about0.4:1 to 5:1.

11. A germicidal composition as defined in any of claims 8, 9 and 10wherein the alkanoyl taurate is an noctanoyl-substituted taurate,whereby said composition possesses extremely low foaming properties.

12. A germicidal composition comprising a complex of iodine withN-methyl-n-octanoyl sodium taurate, the proportion of said taurate toiodine being within the range of 2:1 to 50:1 and preferably about 5:1 to20:1.

13. A germicidal composition as defined in claim 12 wherein the amountof iodine present is about 0.5 to 2.5% of said composition.

14. A germicidal composition as defined in claim 12 containing an iodideselected from the group consisting of HI and alkali metal iodides in anamount to provide proportions of iodide (I-) to iodine within the rangeof about 0.4:1 to 5:1.

15. A germicidal composition as defined in any of claims 12 to 14containing an amount of an acid selected from the group consisting ofphosphoric acid, hydroxyacetic acid, and mixtures thereof to provide apH below about 4 in intended use dilutions of such composition, andfurther containing an amount, within the range of about 15 to 50% basedon the weight of the iodine present, of

a nonylphenol ethylene oxide condensate having about 1.5 mols ofethylene oxide per mol of nonylphenol.

16. A germicidal composition comprising a complex of iodine withN-methyl-n-dodecanoyl sodium taurate, the proportion of said taurate toiodine being within the range of 2:1 to 50:1, and preferably about 5:1to 20: 1.

17. A germicidal composition comprising a complex of iodine withNcyclohexyln-octanoyl sodium taurate, the proportion of said taurate toiodine being Within the range of 2:1 to 50:1, and preferably about 5:1to 20:1.

18. A germicidal composition comprising a complex of iodine withN-ethyl-n-octanoyl sodium taurate, the pro- 8. portion of said taurateto, iodine. being within the range of 2:1 to 50:1, and preferably about5:1 to 20:1.

19. A germicidal compositioncomprising arcomplex of iodine withN-ethyl-n-dodecanoyl sodium tam-ate, the proportion of said taurate toiodine being within the range of 2:1 to 50:1, and preferablyv about 5:1to 20:1.

References Cited in the file of this patent UNITED STATES PATENTS2,977,278 Shelanski Mar. 28, 1961

1. A GERMICIDAL COMPOSITION COMPRISING A COMPLEX OF IODINE WITH ANALKANOYL TAURATE OF THE FORMULA: